Many veteran technicians have encountered this issue: during operation, the striking frequency of a full-hydraulic electro-hydraulic hammer suddenly drops, drastically slowing down processing efficiency. After thorough inspection, the air cylinder and hydraulic valves are found free of faults or jamming. In most cases, the core problem boils down to insufficient oil pump flow. The principle behind this malfunction is straightforward, as explained below.
The oil pump acts as the “heart” of the electro-hydraulic hammer, supplying hydraulic oil to sustain normal striking frequency. Low striking frequency essentially means the pump fails to deliver adequate oil volume per unit time. The common causes are summarized as follows:
- Severe Internal Leakage Caused by Pump Wear With prolonged service, the clearance between the pump plungers and valve plate widens. High-pressure hydraulic oil leaks back to the oil tank inside the pump before reaching the hammer head. Flowmeter testing will show a sharp drop in pump displacement, which inevitably reduces striking frequency.
- Stuck Adjustment Mechanism of Variable Displacement Pump Most electro-hydraulic hammers adopt constant-power variable pumps. If the variable piston gets stuck at a small displacement position, the system will continuously operate at low flow regardless of throttle input, resulting in permanently low striking frequency.
- Poor Oil Suction Performance A clogged oil suction filter or aged, collapsed suction hose hinders the pump’s oil intake and drastically cuts down flow output. This issue becomes more prominent in summer under high oil temperature: thinner hydraulic oil creates greater suction resistance for the pump.
Troubleshooting Procedures
- Check the pump’s pressure and flow readings first. If pressure remains normal while flow is insufficient, prioritize inspecting the variable displacement adjustment mechanism.
- If both pressure and flow are abnormally low, disassemble and inspect the pump for internal wear.
- Inspect the return oil filter for copper or iron debris; heavy metal particles are definitive evidence of pump wear.
Other factors such as low motor speed and slipping couplings can also affect flow, yet they account for far fewer malfunctions in actual maintenance compared to pump-related defects. Focus troubleshooting on oil pump flow, and nine out of ten frequency failures can be resolved. Mechanical maintenance does not require complicated guesswork—follow the entire hydraulic oil circuit, and the fault will be easy to locate.
